The present invention relates to prosthetic devices, and more particularly, to a shuttle lock for securing a patient""s residual limb in a prosthetic limb socket.
Conventional shuttle locks for securing a patient""s residual limb in a prosthetic limb socket are typically disc-shaped and mounted within a distal end of the prosthetic limb socket. The shuttle locks typically include an axial hole extending therethrough and include a spring-loaded, reciprocating pawl cooperating with the axial hole to engage the sloping teeth of a ratcheted plunger pin extending from a distal end of a covering carried on the patient""s residual limb. Accordingly, when the patient wishes to don the prosthetic limb, the patient will first don the covering onto his or her residual limb such that the plunger pin extends distally therefrom and will then insert the residual limb into the prosthetic limb socket such that the plunger pin is received within the axial hole of the shuttle lock and is secured therein by the spring-loaded pawl. Such shuttle locks will also include a release mechanism that removes the pawl from the axial hole of the shuttle lock so that the patient can disengage the plunger pin from the shuttle lock and thus remove his or her residual limb from the prosthetic limb socket.
Although most shuttle locks include a substantially concave proximal surface, where the axial hole centers at the bottom of the concavity, to facilitate locating the plunger pin into the center hole of the shuttle lock, it is sometimes a problem for the patients to locate the center hole of the shuttle lock while inserting his or her residual limb into the prosthetic limb socket. Another known problem is that for residual limbs having a more conical or cylindrical shape, the patient may experience undesirable rotation of the prosthetic limb socket with respect to his or her residual limb.
Yet another known disadvantage with conventional shuttle locks is that the design of the shuttle lock allows the plunger pin to xe2x80x9cwigglexe2x80x9d within the axial hole, which leads to wear in the shuttle lock and prosthetic limb socket components. Since the shuttle lock is desirably low in profile (axial thickness) and since, in some cases, substantial radial clearance is provided between the outer diameter of the plunger pin and the inner diameter of the axial hole (to compensate for mis-aligned engagement), excess xe2x80x98playxe2x80x99 results in the plunger pin.
The proximal surface of the prosthetic limb socket and the distal surface of the shuttle lock abutting the proximal surface at the distal end of the prosthetic limb socket are typically designed to be perfectly flat such that when the shuttle lock is bolted into the distal end of the prosthetic limb socket, xe2x80x9cbindingxe2x80x9d will not be experienced between the two abutting surfaces. However, if these two abutting surfaces are not totally flat and/or totally parallel, binding of the plastic shuttle lock may occur, which could lead to damage of the shuttle lock and/or the prosthetic limb socket.
Accordingly, a need exists for an improved shuttle lock which assists a patient in locating the axial hole of the shuttle lock with the plunger pin extending from his or her residual limb; a shuttle lock in which the plunger pin is stabilized within the axial hole when secured therein so as to reduce wear on the shuttle lock and/or prosthetic limb socket components; a shuttle lock which reduces the chances of binding between the abutting surfaces of the shuttle lock and prosthetic limb socket; and a shuttle lock that is easier to fabricate and maintain.
One aspect of the present invention provides a shuttle lock for maintaining a patient""s residual limb in a prosthetic limb socket, where the shuttle lock includes (a) a housing having a distal surface adapted to abut an inside surface of a prosthetic limb socket, a substantially concave proximal surface and a hole extending into the center of the proximal surface, where the hole is adapted to receive a plunger pin carried on a patient""s residual limb; (b) a lock positioned within the housing for securing the plunger pin received in the axial hole; and (c) means for securing the housing of the shuttle lock within the prosthetic limb socket; (d) where the concave proximal surface includes at least one radial groove which is adapted to guide the plunger pin into the axial hole. Preferably the housing is substantially cylindrical in the concave proximal surface includes a plurality of the radial grooves circumferentially distributed thereabout, where the radial grooves extend substantially from and outer circumference of the concave proximal surface to an outer circumference of the axial hole. It is preferred that the lock involves a spring-loaded pawl positioned within the housing for engagement with a ratcheted plunger pin; however it is within the scope of the present invention to provide other forms of locks suitable for securing the plunger pin within the axial hole extending into the shuttle-lock housing, such as a magnetic lock, for example.
Another aspect of the present invention provides a shuttle lock for maintaining a patient""s residual limb in a prosthetic limb socket that includes: (a) a housing having a distal surface adapted to abut an inside surface of a prosthetic limb socket, a hole extending axially therethrough and adapted to receive a plunger pin carried on a patient""s residual limb; (b) a lock positioned within the housing for securing the plunger pin received in the axial hole; (c) means for securing the housing within a prosthetic limb socket; and (d) an annular protrusion extending distally from the distal opening of the axial hole, where the annular protrusion is coaxial with the axial hole and has an inner diameter substantially equal to the diameter of the axial hole so that the annular protrusion assists in stabilizing the plunger pin when received within the axial hole. Preferably, the protrusion extends through a hole in the prosthetic limb socket and has a height substantially equal to the thickness of the prosthetic limb socket material. Furthermore, it is preferred that the axial hole extending through the shuttle lock is provided by a hardened or metal bushing extending axially through the housing and distally from the housing to provide the annular protrusion. This bushing provides reinforcement to the shuttle lock and substantially reduces the amount of wear imparted by the plunger pin onto the shuttle lock components due to its hardness and wear characteristics.
Another aspect of the present invention provides a shuttle lock for maintaining the patient""s residual limb in a prosthetic limb socket that includes: (a) a housing having a distal surface, a substantially concave proximal surface and a hole extending into the center of the proximal surface which is adapted to receive a plunger pin carried on a patient""s residual limb; (b) a lock positioned within the housing for securing the plunger pin received in the axial hole; (c) a plurality of holes or bores extending into the distal surface of the housing for receiving a corresponding plurality of bolts or screws which are used to secure the housing within the prosthetic limb socket; and (d) at least one projection extending from the distal surface of the housing, where the projection is adapted to abut an inside surface of the prosthetic limb socket and assume the majority of the load distribution when the shuttle lock is secured in the prosthetic limb socket. By reducing the load distribution on the distal surface of the housing, the projection thereby substantially reduces xe2x80x9cbindingxe2x80x9d between the distal surface of the housing and the inside surface of the prosthetic limb socket. Preferably, the distal surface of the housing is substantially flat and the projection has a substantially flat distal surface on a plane parallel to the distal surface of the housing. It is also preferred that there are a plurality of projections, where each projection is substantially annular and surrounds a respective one of the bores, and that the projections extend distally for a distance equal to approximately 0.001 to 0.020 inches.
Another aspect of the present invention provides a shuttle lock for maintaining a patent""s residual limb in a prosthetic limb socket that includes: (a) an upper housing plate having a substantially concave proximal surface, a distal end and an axial hole extending completely therethrough, into the center of the substantially concave proximal surface and out through the distal end; (b) a lower housing plate having a proximal end removably coupled to the distal end of the upper housing plate, a distal surface adapted to abut an inside surface of a prosthetic limb socket and an axial hole extending into the proximal end, coaxial with the axial hole extending through the upper housing plate and adapted to receive a ratcheted plunger pin carried on a patient""s residual limb; (c) a spring-loaded pawl, mounted within the lower housing plate for reciprocation radially into and out from the axial hole extending into the lower housing plate, and adapted to engage the plunger pin received in the axial hole; and (d) means for securing the lower housing plate within the prosthetic limb socket. Preferably, the distal end of the upper housing plate and the proximal end of the lower housing plate are substantially flat.
It is also preferred that the shuttle lock includes: (e) a push rod slidably received within the lower housing plate; (f) a lever, mounted to the lower housing plate, operatively coupled between the push rod and the pawl such that movement of the push rod to a first position causes the pawl to reciprocate at least partially into the axial hole and movement of the push rod to a second position causes the pawl to reciprocate out from the axial hole; and (g) a spring biasing the push rod to the first position. Preferably, the pawl is slidingly positioned in a first radial hole extending into an outer circumferential surface of the lower housing plate and out through the axial hole extending into the lower housing plate, the push rod is slidably positioned in a second radial hole extending into the outer circumferential surface of the lower housing plate, the lever is pivotably mounted to the flat proximal surface of the lower housing plate; and the shuttle lock further comprises a first pin extending from the first end of the lever, through an opening in the flat proximal surface of the lower housing plate and into the push rod, and a second pin extending from a second end of the lever, through an opening in the flat proximal surface of the lower housing plate and into the pawl. This second pin extending through a proximal surface of the lever is preferably slidingly removable from the lever and pawl so as to facilitate simple replacement of the pawl in the lower housing plate. Because the pawl is slidingly received in the first radial hole, once the second pin is removed, the pawl can be slid out from the lower housing plate and replaced if damaged or worn.
Another aspect of the present invention provides a prosthetic limb that includes: (a) a covering adapted to be worn on a patient""s residual limb, where the covering includes a plunger pin extending from a distal end of the covering; (b) a prosthetic limb socket adapted to receive the patient""s residual limb with the covering worn thereon; and (c) a shuttle lock mounted within the prosthetic limb socket, at a distal end of the prosthetic limb socket, where the shuttle lock includes a substantially concave proximal surface, a hole extending into the center of the proximal surface for receiving the plunger pin, and a lock for securing the plunger pin within the axial hole. The proximal surface of the shuttle lock includes at least one radial groove and the covering preferably includes a projection extending distally therefrom which is adapted to be received within the radial groove on the proximal surface of the shuttle lock so as to reduce rotation of the patient""s residual limb and covering with respect to the prosthetic limb socket when the plunger pin is secured within the axial hole of the shuttle lock. Preferably, the concave proximal surface of the shuttle lock includes a plurality of radial grooves circumferentially distributed thereabout and the covering includes a plurality of ribs extending distally therefrom and oriented radially with respect to the plunger pin, so that the ribs are adapted to be received within the radial grooves to provide the anti-rotation discussed above.
Accordingly, it is an object of the present invention to provide a shuttle lock adapted to assist a patient in donning a prosthetic limb socket, and specifically, a shuttle lock that assists the patient in locating the axial hole extending through the shuttle lock with the plunger pin extending distally from the covering worn on the patient""s residual limb. It is a further object of the present invention to provide a shuttle lock that is less susceptible to wear, and a shuttle lock that is designed to reduce binding between the shuttle lock housing and the prosthetic limb socket. It is a further object of the present invention to provide a prosthetic limb that is designed to reduce undesirable rotation between the patient""s residual limb with respect to the prosthetic limb socket. Finally, it is an object of the present invention to provide a shuttle lock that is relatively uncomplicated and inexpensive to manufacture; and that is relatively easy to maintain. These and other objects and advantages of the present invention will be apparent from the following description, the attached drawings and the appended claims.